Improved dredging-machine



UNITED STATES PATENT OFFICE.

JOHN JOHNSON,OF SACO, MAINE.

IMPROVED DREDGlNG-MACHINEQ Specification forming part of Letters PatentNo. 56,948, dated August 7, 1866.

To atl whom it may concern:

Be it known that I, JOHN JOHNSON, of Saco, in the county of York andState of Maine, have invented a new and useful Improvement inDredging-li/Iachines; and I do hereby declare that the following is afull and exact description of the same, referencebeing had to theaccompanying drawings, and to the letters and iigures marked thereon.

The main feature of my invention consists in providing a boat, scow, orvessel of suitable size and shape, which at pleasure, can be made airand water tight. To this vessel I attach a suitable tube or trunk insuch a manner that it may be lowered at one end upon the material thatis to be dredged. When so placed, I remove, by suitable machinery, theair or water from the interior of the dredging-vessel, causing a partialvacuum, and the material to be dredged is elevated through the tube intothe scou' or other vessel by the pressure of the atmosphere.

Figure I is a perspective view of the apparatus. Fig. II is alongitudinal section. Fig.

III is a section of the cross-tube and valves. Fig. IV is an elevationof the pumps. j

The barge or scow is made of suitable size for the intended purpose andstrong enough to sustain the required pressure when the interior isexhausted of air or Water. l .In the center of the vessel, or near it,there is a suitable well-chamber, B, large enough to admit a person topass down from the deck D to reach and open the cap or valve C on theend of the tube E, to afford opportunity for the removal of obstructionsfrom the crossed portion K L at the inboard end of the tube E, in casethe passage into the barge or receptacle becomes choked and the dredgerrendered inactive.

The bottom of the barge is provided with a suitable seat and valve, V,for the purpose of discharging the dredged contents. This valve can beclosed or opened at pleasure by means of the screw F. The shaft of thescrew passes through the stuffing-box G, and is connected with the valveby the chain H.

Along the center of the barge,'and in continuation of the well B, it isdesirable to construct a recess, M, toward the rear, so that the tube EJ, when not in use, may be raised to a horizontal position. The tube E Jis made of strong sheet-iron, firmly riveted. The end where it entersthe barge at either side, as at I I', Fig. III,is in the form of across, and may be made of castiron. Its ends are turned to lit thebearingsW W,'aud are made watertight.

At the outer end, J, of the tube E J counection is madewith a similartube, N, by means of a flexible joint, P, or a ball-and-socket joint.When the machine is at work this joint relieves the strain upon thejournals I I"of the crosstube K L.

The outer end of the tube N is bell-shaped, as at O, in order that itmay present a larger surface to the mud or sand than the area ofthemouth of the tube. Near the outerA end of this tube there isa ring, Q,to which a tackle is secured, extending to a crane or capstan on deck,for the purpose of raising or lowering the tube.

The barge A having been lled with water to its water-load line throughthe valve V, or other suitable opening, the valveis then closed, thetube E JNis lowered until its foot O rests upon the mud, sand, or othermaterial ,to be dredged. The pumps X are then put in operation, and thewater is discharged at the orifice T, just above the Water-line, therebycausing a partial vacuum in the barge. The atmospheric pressure upon thewater outside forces up the mud or sand, which passes up the tube and isdeposited within the barge. Thus as the water is removed the sand takesits place, sufficient Water being combined with the sand to render itsemi-fluid and capable of transit from below to the barge above.

While the barge is being filled it becomes necessary gradually to warpit forward, sothat an even depth may be excavated or dredged.

To prevent any portion of the dredged materials from returning throughthe cross and tube there are flap-valves R Rat the mouths of thecross-tube K L. During the action of the pumps these valvesremain-partially open, and when the pumps stop they close by gravity andthe pressure of the sand that is near them.

When the bargeis lilled tothe load-line, and just before the pumps arestopped, it is desirable to hoist the end of the tube N O, so that allthe mud and contents may be drawn up and deposited within the barge.This in-` sures a free tube ready for the next load. The barge is nowmoved to the place of deposit, the valve or trap V is opened, the sandfalls out and is deposited on the bottom. The barge immediately iillswith water. The valve V is now closed by means of the screw and chain HF, and the water may be pumped out, provided the Hap-valves R R are madetight. This may be done while the bargeis returning to the locality fordredging. The tube being again lowered to the bottom, the valves arereleased and the pumps again putin operation.

The barge is provided with air-tight compartments S S', of sufficientbuoyancy to oat the boat when fully loaded.

The pump-wellY is situated within a bulkhead U, the top of which isabout level with the top ofthe load of dredged material. The water whichenters the barge with the sand or mud flows over the top of thisbulk-head and into the well.

The important features of this invention for dredging are that the inudor sand can be removed from the place of accumulation into the bargewithout elevating it above the waterlevel, the materials being lifted ata very small cost for power compared with that required to dredge wherethe whole of the gravity of the mass has to be overcome. The mechanismis less expensive and its management less difcult than that of dredgersheretofore made.

In the direct application of the apparatus, where the air or water isremoved and the mud or sand occupies its place, a very little tensionper square inch is necessary, as the submerged material moves freely,being permeated by water, and its weight is about twofifths less than itis in the air.

What I claim, and desire to secure by Letters Patent, is-

1. The system or mode of dredging, consisting of an air-tight iiexiblesupply-tube, an airtight floating barge or vessel, and suitable pumpsfor removing air or water from the vessel. substantially as hereindescribed.

2. In combination with an air-tight oating barge, the discharge-valve Vand the bulkheads that allow the Water to flow over them into thepump-well as it is displaced by the entrance of sand or other dredgedmaterials.

3. The cross-tube K L, in combination with the main supply-tube, asspecified.

et. The combination of the cross-tube K L with its bearings I I', forthe purpose of raising and lowering the tube without disturbing theposition of the orices through which the mud or sand passes.

5. The combination ot' the cross-tube with the cap or stopper O, so ttedthat it can be taken off for the purpose of lremoving.; obstructions,substant-ially as herein set forth.

JOHN JOHNSON.

In presence of- Jos. L. MILLIKEN, Jos. S. MOODY.

